1. Field of the Invention
The present invention relates to a hand-held power tool with a locking nut for securing a disc-shaped tool and, in particular, to angle grinder, hand-held jointer saw, or hand-held circular saw.
2. Description of the Prior Art
Conventional tool holders for a disc-shaped tool (under which in addition to flat discs, also plate-shaped tools are understood) frictionally secure the disc-shaped tool on the rotatable drive spindle between a clamping flange provided on the drive spindle and a locking nut that is screwed onto the drive spindle. The thread direction of the locking thread provided on the drive spindle is usually so selected that the locking nut automatically tightens upon actuation of the power tool or start up of the operation. A drive spindle provided with a locking thread on its free end is disclosed in German Publication DE 311 09 12.
Contemporary hand-held power tools with safety routines provide for sudden braking of the drive spindle up to a complete stop. In order to reliably prevent an inadvertent loosening of the locking nut and/or of the disc-shaped tool in case when the locking nut becomes loose due to its inertia upon a sudden stop of the spindle, German Publication DE 42 38 466 discloses locking means that in addition to a locking nut, includes additional clamping means that applies pressure to the disc-shaped tool and is preloaded against a locking nut with a plate spring.
An object of the present invention is to provide a reliable tool holder for a disc-shaped tool and that includes a locking nut.